Four people in Montreal have locked themselves to the gates at SUNCOR oil refinery in the city's east end.

In a release issued this morning, the demonstrators explained that their action is to counter the reversal of Enbridge's Line 9B oil pipeline. The reversal in the pipeline's flow will bring bitumen from the Alberta tar sands east, through including through Montreal, for eventual export.

"If we're gotten to the point of taking this kind of action, it's because there are no other means for our voices to be heard," Alyssa Symons-Bélanger, one of the protesters taking part in the action, said via press release. "We want to send a clear message to the oil companies and to the Harper and Couillard governments: the residents of Quebec are opposed to the transportation of the tar sands and are calling for an immediate halt to their extraction."

According to tweets from people on site, Montreal police had arrived before 7am, and were considering what action, if any, they should take.

Residents of Quebec opposed to the pipeline have been working to rally public opinion against the project. Over the summer, more than two dozen people walked 700km across the province to protest Enbridge's Line 9 and TransCanada's Energy East pipeline (which would also bring tar sands bitumen east through the province). And for the last two weeks, ending this past Sunday, climate justice activists gathered for an action camp in rural Quebec to discuss and strategize how best to counter Line 9, and the problem of the growing oil extraction in the tar sands, including the impact on communities both in Northern Alberta and along the route of pipelines beading both east and west.

Blockades of Line 9 terminals and Enbridge work sites have also taken place in Ontario over the past year.

The Line 9 reversal will bring 300,000 barrels of tar sands bittumen through Quebec each day.